How to speed jenkins build process while installing requirements using pip

Question

I am using Jenkins CI for my django project. For Django-Jenkins integration I am using the django-jenkins app. In the build step of Jenkins I create a fresh virtualenv and install all the dependencies for each build using requirements file. However, this makes build extremely slow because a fresh copy of all the dependencies must be downloaded from a PyPI mirror, even if nothing has changed in the dependencies since the last build. So I started using the local caching built-in to pip by setting the PIP_DOWNLOAD_CACHE environment variable. But the whole build process is still painfully slow and takes more than 10 minutes. Is there any way I could speed up the whole process? Maybe by caching the compiled dependencies or something else?

Answer 1

Just only install a fresh virtualenv if your requirements.txt file changes. This can be done easily with some shell commands. We are doing something similar in one of our projects. In a Jenkins shell window we have (after svn up):

touch changed.txt
stat -c %Y project/requirements.txt > changed1.txt
diff -q changed.txt changed1.txt || echo "DO YOUR PIP --upgrade HERE!"

Answer 2

Why bother creating a fresh virtualenv each time you build? You should be able to create just one and simply activate it with . /path/to/venv/bin/activate as an 'Execute shell script' build step (assuming the use of linux here). Then, if you need to install a new dependency, you can activate the venv on your own and pip install the new package.